FIGURE 9.

Synchrotron IR microspectroscopy comparison of mock, WT, and F2-infected A549 cells at 24 h post-infection within the CH region. A, score plot of PCA from the 3100–2800 cm⁻¹ band IR spectra. The explained variance for PC1 and PC2 is 87 and 3%, respectively. Marked data with a red triangle correspond to A549 cells infected with WT virus, black circles to cells infected with F2 virus, and white squares to mock-infected cells. B, loading plot linking the variable space and principal component subspace (PC1). PCA score plots show that the WT and F2-mock groups separate along PC1. C, mean IR spectra of mock-infected cells (black line) and WT-infected cells (red line) at 24 h post-infection in the 2980–2840 cm⁻¹ range. The bands assigned to CH3 symmetric/asymmetric (2958 and 2873 cm⁻¹, respectively) were more intense for WT-infected cells than for mock-infected cells. The contrary was observed for bands assigned to CH2 symmetric/asymmetric (2924 and 2852 cm⁻¹, respectively). PC, principal component.